Simulation-based shop floor control

Journal of Manufacturing

Systems

VoL21/No.6 2002

2000-2002 abstract and kevword index er stress can be applied to shear off the bolt head with the same amount of energy invested as in a single wave impact. The results can be used to design effective destructive disassembly procedures and new demanufacturing tools resulting in an increase of disassembly efficiency and a reduction of recycling cost. Keywords: Destructive Disassembly, Impact Fracture, Stress Wave, Demanufacturing

Journal of Manufacturing

Further, the new interface scheme will impact the CADCAM-CNC process chain and the advancement of the CNC controller. This paper develops an integrated STEP-compliant CNC system (or STEP-CNC) based on the new interface scheme. The system is composed of five modules: (1) Shop Floor Programming System (PosSFP), (2) Tool Path Generator (PosTPG), (3) Tool Path Viewer (PosTPV), (4) Man Machine Interface (PosMMI), and (5) CNC Kernel (PosCNC). The developed system is a prototype but very comprehensive, including all the modules required for realizing “art-to-part” through the new CAD-CAM-CNC chain. Architecture and functional details are presented together with a realistic demonstration. Keywords: STEP-NC, IS0 14649, STEP-Compliant CNC, Shop Floor Programming, Soft-NC, Intelligent CNC, STEP Manufacturing

Systems

Volume 21, Number 5,2002 Sheet Metal Bending: Forming Part Generating Shared Press-Brake Setups,

Families

for

Satyandra K. Gupta, Deepak Rajagopal, ~21, n5,2002, ~~329-349 Sheet metal bending press brakes can be set up to produce more than one type of part without requiring a setup change. To exploit this flexibility, setup planning techniques are needed so that press-brake setups can be shared among many different parts. This paper describes algorithms for partitioning a given set of parts into setupcompatible part families that can be produced on the same setup. First is presented a greedy algorithm to form a part family using a bottom-up approach that makes use of the mixed-integer linear programming formulation for generating shared setups for each part family. Second is presented a mixed-integer linear programming formulation to generate a shared setup for a given set of parts if such a setup exists. By producing many different types of parts on the same setup, it is expected that there will be significant reductions in the number of setup operations, improved machine tool utilization, and more cost-effective small-batch manufacturing. Keywords: Computer-Aided Process Planning, Setup Design, Part Family Formation, Sheet Metal Bending

Determining Operating Criterion of Batch Processing Operations for Wafer Fabrication, Nipa Phojanamongkolkij,

John W. Fowler, Jeffery K. Co&ran, v2 1, n5,2002, ~~363-379 All semiconductor manufacturing systems involve batch processing operations. These operations can have a on product cycle times. significant impact Semiconductor manufacturers are often interested in batch processing policies that minimize the sum of the weighted cycle time of all products, where the weights indicate the priority levels of products. A well-known minimum batch size (MBS) policy is generally recognized as an effective policy. However, there is no guideline in determining the minimum batch sizes to start batch processing operations for this policy. This paper illustrates the use of an analytical queuing model to determine these minimum batch sizes. Illustrations of the effectiveness of the approach are provided through a comparison simulation study of various batch processing policies of a real-world semiconductor manufacturer with multiple products and with small to medium volumes. The comparison results suggest that using an analytical queuing model to determine batch sizes for the MBS policy gives a better minimum sum of the weighted cycle time of all products than the other policies considered. Keywords: Batch Processing, Queuing, Simulation, Batch Processing Policy, Semiconductor Manufacturing

Developing an Integrated STEP-Compliant CNC Prototype, S.H. Suh, D.H. Chung, B.E. Lee, J.H. Cho, S.U.

Cheon, H.D. Hong, H.S. Lee, ~21, n5,2002, ~~350-362 STEP-compliant CNC is the next-generation CNC controller, taking the STEP-NC data model as the interface scheme between CAM and CNC and carrying out various intelligent functions, At the moment, efforts are being made worldwide to establish an international standard for the new interface scheme (so-called STEP-NC), formalized as IS0 14649. In the near future, the new interface scheme will be completed and announced as the international standard. Upon completion, the standard will replace the conventional scheme based on IS0 6983, so-called M&G codes.

Shop Floor Control, Young-Jun Son, Sanjay B. Joshi, Richard A. Wysk, Jeffrey S. Smith, v2 1, n5, 2002, ~~380-394 This paper presents an overview of simulation-based shop floor control. Much of the work described is based on research conducted in the Computer Integrated

Simulation-Based

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Journul oj.Manufacturing Systems Vol. 21/No. 6 2002

2000-2002 abstract and keyword index Manufacturing (CIM) Lab at The Pennsylvania State University, the Texas A&M Computer Aided Manufacturing Lab (TAMCAM), Technion in Israel, and the University of Arizona CIM lab over the past decade. In this approach, a discrete event simulation is used not only as a traditional analysis and evaluation tool but also as a task generator that drives shop floor operations in real time. To enable this, a special feature of the Arena simulation language was used whereby the simulation model interacts directly with a shop floor execution system by sending and receiving messages. This control simulation reads process plans and master production orders from external databases that are updated by a process planning system and coordinated via an external business system. The control simulation also interacts with other external programs such as a planner, a scheduler, and an error detection and recovery function. In this paper, the architecture, implementation, and the integration of all the components of the proposed simulation-based control system are described in detail. Finally, extensions to this approach, including automatic model generation, are described. Keywords: Shop Floor Control, CIM, Real-Time Scheduling, Simulation

select the best model. Data from industrial experiments based on fractional factorial design will illustrate the goodness of the modeling approach and the models. Keywords: Surface Roughness, Neural Networks, Honing, IS0 13565, Factorial Design of Experiments

Journal of Manufacturing Systems Volume 21, Number 6,2002 Closed-Loop Real-Time Cooperative Decision-Making Dynamics in Heterarchicai Manufacturing Systems, Neil A. Duffie, Vittaldas V Prabhu, Patrick 0. Kaltjob, ~21, n6, 2002, ~~409-418 Distribution of control in heterarchical manufacturing systems creates challenges in making and modeling cooperative decisions, such as when to produce discrete parts on multiple manufacturing machines. Furthermore, the dynamics of decision-making interactions between highly autonomous entities in these systems are poorly understood and can be undependable because of the absence of a master controller or optimizer. To investigate these phenomena, a system for distributed control of the arrival time of discrete parts in multiple-machine, multiple-processingstep manufacturing systems has been developed and is described in this paper. In the system, continuous control laws replace heuristics, and part arrival times are adjusted locally using feedback of expected completion times. The reported results confirm that the dynamics of the distributed systems are favorable, with arrival times converging exponentially to theoretically predictable values regardless of whether or not a set of arrival times exists that, given the machine resources available, results in parts being completed on their due dates. In the paper, closed-form solutions are obtained for nonlinear, discontinuous differential equations that describe system behavior in different dynamic regions and explain arrival time convergence and intrinsic cooperation between discrete parts in their competition for production machinery. Furthermore, the systems are shown to be responsive to real-time disturbances that can be caused by rush orders, machine failures, and changes in part processing times. These results build confidence in design, implementation, and operation of distributed control systems for manufacturing, regardless of whether they are heuristic or control-law based even though they appear to behave in a chaotic manner due to the interactions of highly autonomous entities. k’eywords: Distributed Control, Decision Making, Scheduling

Neural Networks Modeling of Honing Surface Roughness Parameters Defined by IS0 13565, Chang-Xue (Jack) Feng, Xianfeng (David) Wang, Zhiguang (Samuel) Yu, v2 1, n5,2002, pp395-408 For decades, the arithmetic average (AA or k) and root sum of squares (RSS or Rg) have been the two major surface roughness measures to define a broad range of surfaces for a mechanical product. A number of drawbacks have been identified in recent years with the above measures. To map more scientifically and closely the surface roughness to the product functions and performances, IS0 13565 has defined a different set of measures, including Rk, R+ Rvk, M,,, and Mr2. This has not only made process planning different and much more difficult, but also made modeling of the relationship between these roughness measures and the machining parameters a multiple-input and multiple-output problem. While some companies are trying the traditional trialand-error method to implement the IS0 13565 standard this study applies artificial neural networks to develop an empirical model for the honing process of engine cylinder liners in order to help reduce emissions, improve oil efficiency, and prolong engine life. Threefold cross-validation is applied to develop the models. Hypothesis testing and the prediction error statistics are employed to

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